Method of manufacturing sliding clasp fasteners



May 1955 G. WARBURTON ETAL 2,744,313

METHOD OF MANUFACTURING SLIDING CLASP FASTENERS Filed April 19, 1955 Altorney United States Patent METHOD OF MANUFACTURING SLIDING CLASPFASTENERS Geoflrey Warburton, Cardilf, and William J. P. Clarke,Glamorgan, Wales, assignors to Aero Zipp Fasteners Limited, London,England, a British company Application April 19, 1955, Serial No.502,449

Claims priority, application Great Britain November 9, 1954 20 Claims.(Cl. 29-408) The present invention relates to a method of making slidingclasp fasteners. For some purposes, for example in trouser flies,sliding clasp fasteners are used, the stringers of which (that is to saythe fastener tapes provided with interlocking members) are curved in thegeneral plane of the stringers. In order to obtain the desiredcurvature, it has been proposed to attach the interlocking members tothe fastener tapes at distances between adjacent interlocking memberswhich vary along the stringers and/or to vary the shape of theinterlocking members along the stringers.

It is an object of the invention to provide a curved sliding claspfastener without necessarily varying the spacing between adjacentinterlocking members while attaching them to the fastener tapes and/orvarying the shape of the interlocking members along the stringers.

It is another object of the invention to provide a method of curving asliding clasp fastener after the interlocking members have been attachedto the tapes.

To make the invention clearly understood reference will now be made tothe accompanying drawings, which are given by way of example, and inwhich:

Fig. 1 illustrates a length of a pair of sliding clasp fastenerstringers;

Fig. 2 is a somewhat diagrammatical perspective view of an arrangementfor performing the method; and

Fig. 3 illustrates a pair of curved sliding clasp fastener stringers.

Fig. l of the drawings illustrates a length of a pair of stringers 1 and2, as they are normally produced in the manufacture of sliding claspfasteners.

The two stringers 1 and 2 are interlocked with each other byinterengaging the interlocking members 3 and 4 of the stringers 1 and 2.Before or after the interlocking, a starching or sizing liquid, forexample a synthetic starch of a semi-permanent nature consisting of anaqueous dispersion of a thermoplastic synthetic resin, such as a vinylacetate polymer, is applied to the stringers 1 and 2 or a part thereofwhich has to be curved, and the interlocked stringers 1 and 2 are thentightly drawn around a heated conical surface 5 (see Fig. 2) of amandrel 6 and while tensioned are held by suitable means (not shown)against the conical surface 5 for an appropriate period, to dry orpartially to dry the stringers 2 and 3, whereupon the said stringers areremoved from the conical surface 5 and flattened out. The stringers 1and 2 are now curved as shown in Fig. 3. For applying the starching orsizing liquid, the same may be sprayed onto the stringers, or thestringers may be dipped once or several times into a supply of theliquid.

By suitably choosing the sizing or starching liquid it can be achievedthat the stringers 1 and 2 retain the curvature imparted thereto even ifthe sliding clasp fastener comprising the stringers is washed a fewtimes. However, in some cases it may not be essential that the starchingor sizing material remains effective after washing or dry cleaning. Forexample, when sliding clasp 2,744,313 Patented May 8, 1956 ice fastenersare to be fixed to trouser flies, it may be immaterial whether thestarching or sizing material does or does not retain their shape afterwashing or dry cleaning once they have been fixed to the trouser flies,since the trouser flies will retain the shape of the sliding claspfasteners.

Modifications of the specific method described are possible. Forexample, a single stringer may be treated in a manner similar to thatdescribed with respect to the pair of stringers 1 and 2. Again, theconical surface 5 may be replaced by any other suitably shaped curvedsurface. For instance, the curved surface may be ellipsoidal. The curvedsurface may be a closed curved surface in which case the stringer orstringers may be wound once or several times around the surface. Thestarching or sizing material may be applied, for example by spraying ordipping, after the stringers have been drawn or wound around the curvedsurface. Instead of drawing or winding the stringer or stringers tightlyaround the curved surface, they may be placed loosely against the sameand may be shrunk onto the curved surface by wetting the stringer orstringers. Instead of using a liquid sizing or starching material, thestringer or stringers may be initially dry, but coated or impregnatedwith a sizing or starching material and may subsequently be wetted. Themandrel may be heated for accelerating the drying of the stringers. Ifdesired, a former may be employed which has a concavely curved surfacemating the curved surface of the mandrel 6 and which may be heated, thesaid former being, in use, pressed against the mandrel with the stringeror stringers sandwiched between the mandrel and the former whereby toapply pressure and/ or heat (if the former and the mandrel are bothheated) to the stringer or stringers from each side thereof.

Instead of using a starching or sizing material, a plastic material maybe employed which, after the stringer or stringers have been curved, iscaused to set, for example by the application of heat. The stringer orstringers may be coated or impregnated with the plastic material, orelse threads of the plastic material may be woven into the stringers,the threads being responsive to the setting treatment. Such threads maybe made of polyvinyl chloride.

It will be appreciated that the method may be applied to the stringer orstringers after the interlocking members have been attached to thecarrying tapes. Thus, the method does not interfere with the usualmethods of making sliding clasp fastener interlocking members and ofattaching the same to the carrying tapes.

We claim:

1. A method of manufacturing a sliding clasp fastener which, at least inpart, is curved in the general plane of the fastener stringers,comprising the steps of imparting a curvature to at least one of thestringers by stretching at least a part thereof, and applying a materialto the said stringer which substantially maintains the curvatureimparted to the stringer by the stretching.

2. A method of manufacturing a sliding clasp fastener, which at least inpart, is curved in the general plane of the fastener stringers,comprising the steps of imparting a curvature to at least one of thestringers by shrinking at least a part thereof, and applying a materialto the said stringer which substantially maintains the curvatureimparted to the stringer by the shrinking.

3. A method of manufacturing a sliding clasp fastener which, at least inpart, is curved in the general plane of the fastener stringers,comprising the steps of imparting a curvature to at least one of thestringers by deforming at least a part thereof, and applying a materialto the said stringer which substantially maintains the curvatureimparted to the stringer by the deformation.

4. A method as claimed in claim 3, wherein two stringers are interlockedwith each other by interengaging their interlocking members, and theinterlocked stringers or parts thereof are jointly deformed.

5. A method as claimed in claim 3, wherein the material applied to thestringer is a starching material.

6. A method as claimed in claim 5, wherein the starching material is asynthetic starch consisting of an aqueous dispersion of a thermoplasticsynthetic resin.

7. A method as claimed in claim 6, wherein the thermoplastic syntheticresin is a vinyl acetate polymer.

8. A method as claimed in claim 3, wherein the material applied to thestringer is a sizing material.

9. A method as claimed in claim 3, wherein the material is applied bycoating the stringer therewith.

10. A method as claimed in claim 3, wherein the material is applied byimpregnating the stringer therewith.

11. A method of manufacturing a sliding clasp fastener which, at leastin part, is curved in the general plane of the fastener stringers,comprising the steps of imparting a curvature to a stringer, in which asettable plastic material is incorporated, by deforming at least a partof the stringer, and causing the plastic material to set after the saidstringer portion has been deformed, whereby to maintain the curvatureimparted to the stringer by deformation.

12. A method as claimed in claim 11, wherein the stringer comprisesthreads made of the settable material.

13. A method as claimed in claim 12, wherein the threads are made ofpolyinyl chloride.

14. A method of manufacturing a sliding clasp fastener which, at leastin part, is curved in the general plane of the fastener stringers,comprising the steps of stretching at least a portion of at least one ofthe stringers tightly around a convexly curved surface to curve the saidstringer, and applying a material to the said stringer whichsubstantially maintains a curvature of the stringer, subsequentlyremoving the said stringer from the said surface, and flattening it out.

15. A method as claimed in claim 14, wherein the convexly curved surfaceis a conical surface.

16. A method as claimed in claim 14, wherein the convexly curved surfaceis heated.

17. A method of manufacturing a sliding clasp fastener which, at leastin part, is curved in the general plane of the fastener stringers,comprising the steps of placing at least a portion of at least one ofthe stringers loosely around a convexly curved surface, wetting the saidstringer to shrink it on to the said surface to curve the said stringer,and applying a material to the said stringer which substantiallymaintains a curvature of the stringer, subsequently removing the saidstringer from the said surface, and flattening it out.

18. A method as claimed in claim 17, wherein the convexly curved surfaceis heated.

19. A method of manufacturing a sliding clasp fastener which, at leastin part, is curved in the general plane of the fastener stringers,comprising the steps of stretching at least a portion of at least one ofthe stringers tightly around a convexly curved surface to curve the saidstringer, and applying a material to the said stringer whichsubstantially maintains a curvature of the stringer, placing a formerhaving an auxiliary curved surface mating the first curved surfaceagainst the said stringer so that the said stringer is sandwichedbetween the first and the auxiliary curved surfaces, heating at leastone of the said curved surfaces for a period of time, subsequentlyremoving the said former, removing the said stringer, and flattening itout.

20. A method of manufacturing a sliding clasp fastener which, at leastin part, is curved in the general plane of the fastener stringers,comprising the steps of placing at least a portion of at least one ofthe stringers loosely around a convexly curved surface, wetting the saidstringer to shrink it on to the said surface to curve the said stringer,placing a former having an auxiliary curved surface mating the firstcurved surface against the said stringer so that the said stringer issandwiched between the first and the auxiliary curved surfaces, heatingat least one of the said curved surfaces to dry the stringer,subsequently removing the said former, removing the said stringer, andflattening it out.

No references cited.

